Variable and reversible pitch fan for



Feb. 14, 1956 cs. WuFlNDLEY 2,734,493 VARIABLE AND REVERSIBLE PITCH FAN FOR INTERNAL COMBUSTION ENGINE Filed Dec. 22, 1952 IN VEN TOR.

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VARIABLE AND REVERSIBLE PITCH FAN FOR INTERNAL-COMBUSTION ENGINE George W. Findley, Birmingham, Mich assignor, by mesne assignments, to Ford Motor Company, Dearborn, Mich., a corporation of Delaware Application December 22, 1952, Serial No. 327,329

3 Claims. c1. 123-4142 This invention relates to an improved fan cooling mechanism for internal combustion engines, and particularly to a variable pitch fan and improved mechanism for controlling the air flow characteristics of such fan as a function of the temperature of the coolant of a liquid cooled internal combustion engine.

It has long been recognized that the air fan conventionally provided on an internal combustion engine is very wasteful of a substantial amount of the power developed by such engine in that the fan is commonly designed to produce an air blast of the intensity required to effect proper cooling of the engine under the most extreme conditions of use and ambient temperature to which the engine may be subjected. In most instances, the engine does not operate under such extreme conditions and the excessive air blast produced by the fan constitutes wasted power.

An additional problem is encountered in the cooling of internal combustion engines utilized in agricultural applications in that clogging of the radiator due to chaff, vegetation or the like is often encountered. This problem is particularly acute on farm tractors and engines employed on various types of harvesting equipment such as combines, forage harvesters, hay balers, and the like. It is necessary for the farmer to be continuously alert to observe the condition of the radiator and to periodically efiect the cleaning of the chaff from the radiator. bviously, such cleaning could be more conveniently and rapidly effected by a mere reversal of the air stream produced by the fan, thus blowing the trash out ofthe radiator.

Accordingly, it is an object of this invention to provide an improved variable and reversible pitch fan for an internal combustion engine and particularly an improved mechanism for controlling the pitch of the blades of the variable pitch fan as 'a function of the temperature of an internal combustion engine.

A particular object of this invention is to provide an improved variable pitch fan and control mechanism therefor which may be conveniently mounted in the same position on an internal combustion engine as the conventional constant pitch fan, and further characterized by the fact that the pitch of such fan is controlled as a function of the temperature of the liquid coolant for the internal combustion engine.

Still another object of this invention is to provide an iimproved air fan and-radiator construction which permits the cleaning oftrash and similar foreign matter from the radiator air passages by the convenient reversal of the pitch of the fan blades.

The specific nature of this invention, as well as other objects and advantages thereof, will become apparent to those skilled in the art from the following detailed description, taken in conjunction with the attached sheet of drawings on which, by way of preferred example only, is illustrated one embodiment of this invention.

Onthe drawings: 1 .7 1

Figure 1 is a sectional view taken on the plane passing "ice through the rotational axis of a variable pitch fan construction embodying this invention, shown in assembled relationship to the radiator and engine block of an internal combustion engine; and

Figure 2 is a sectional view taken on the plane 2-2 of Figure 1.

As shown on the drawings:

The numeral 10 represents an engine block of a conventional internal combustion engine of the type employed in tractors and similar agricultural equipment.

A conventional radiator 11 is provided in spaced relationship to the front engine wall 10a and liquid coolant for cooling the engine is circulated through the finned tubes 11a of radiator 11 in conventional fashion. On the front engine wall 10a a pump housing 12 of conventional construction is mounted by virtue of the bolts 12a and gasket 12b. Pump housing 12 defines an internal annular inlet chamber into which coolant fluid is drawn from the bottom of radiator 11 by the customary hose connection (not shown). Axially adjacent to inlet chamber 120 a pump chamber 12d is defined which communicates with a suitable opening 10b in the engine block wall 10a to provide fluid communication with the coolant passages in the engine. Additionally, pump housing 12 has a forwardly projecting hollow conical extension 12c which mounts a conventional sealed anti-friction type bearing 13. A hollow shaft 14 is journaled in bearing 13, projecting forwardly out of bearing 13 for a purpose to be described and projecting rearwardly into pump chamber 12d. A conventional impeller 15 is mounted on the rearward end of hollow shaft 14 and cooperates with the walls of pump chamber 12d to produce a pumping action on the coolant fluid of the internal combustion engine, thus drawing the fluid through the radiator 11 and discharging it into the engine block from whence it is conducted to the top of radiator 11 in conventional fashion. A seal unit 14c is mounted on the shaft 14 intermediate the impeller 15 and bearing 13 to prevent coolant leakage out of pump inlet chamber 12c.

On the forwardly projecting end of hollow shaft 14, a driving pulley hub 16 is mounted and suitably keyed to shaft 14. Hub 16 has a rearwardly extending sleevelike flange 16a which terminates in an integral pulley portion 16b- Pulley portion 16b is driven by the engine fan belt (not shown) in conventional fashion.

Additionally, the pulley hub 16 is provided with a radial flange 16c and the flange is utilized to mount a blade support or hub 17 for a variable pitch fan. Hub 17 is of generally cup-shaped construction overall having at its open end an axial flange 17m which abuts a similar flange on the pulley hub and is secured thereto by a plurality of bolts 18. Hub 17 is conveniently formed of two co-axial stampings 17a and 17b which have abutting radial flange portions 17c and 17d respectively secured together by bolts 17n. At spaced intervals around the peripheries of flanges 17c and 17d, semicylindrical mating depressions are formed, thus defining angularly spaced cylindrical bores 17f. Bearing sleeves 19 are pressed into each bore 17 A plurality of fan blades 20 are provided, each of such blades having a figuration 20b, as best shown in Figure 2. Hence, the rotation of crank portions 20b will efllect a variation in the pitch of the fan blades 20 and thus change the air pumping characteristics of the fan.

To control the pitch of the fan blades 20, an hydraw. lically'actuated piston 21 is slidably mounted within the i cylindrical bore 14a of the hollow shaft 14. Piston 21-.

has a forwardly projecting rod portion 21a integrally r d. hereon h ch. p oj ts f r dly nt an act ator sleeve 26 which is supported in the end wall 17!: of the fan hub 17. A shifter collar 22 is secured to a medial portion of piston rod 21a and such shifter collar defines an annular external groove 22a which receives each of the crank end portions 20d of the fan blades 29. Thus, movement of piston 21 will produce a change in the pitch of the blades 20 and effect a change in the air pumping characteristics of the fan.

The piston rod 21a, and hence the variable pitch blades 20, are preferably spring biased. to a neutral position which closely approximates the zero pitch position of the fan blades 20. Such biasing arrangement may, for ex ample, comprise a pair of compression springs. 23a and 231; which are respectively engageable with opposite axial ends of shifter collar 22. The other end of spring 230 is bottomed on a radial flange 24a provided on a sleeve 24 which is snugly inserted in a central aperture 17g in the end of hub 17, while the other end of spring 23b is bottomed upon a collar 25 which abuts the end of hollow shaft 14.

To actuate the piston 21, the other end of the bore 14a of hollow shaft 14 is closed by a plug 14d. A suitable charge of a low boiling point fluid is then introduced into the bore 14a. tion of bore 14a defines an hydraulic cylinder cooperating with piston 21, while the other end of bore 14a is disposed in intimate heat transfer relationship with the coolant which is circulated through the engine. Hence,

theaverage temperature of bore 14a will vary as a function of the engine temperature. The low boiling point fiuidwhich is inserted in the enclosed bore 14a is of. the

type that will vaporize at a temperature in the bore 14a corresponding to an engine temperature somewhat below the normal operating temperature and will produce a vapor pressure within the enclosed bore 14a which will increase as a function of the engine temperature. Such fluid shall be hereinafter referred to as a temperature rea sponsive, variable pressure fluid.

It is therefore apparent that the piston 21 will be subjected to a vapor pressure which increases as a function of the engine temperature, thus, producing forward displacement of piston 21 and, piston rod 21a in proportion to the engine temperature. Such forward displacement of piston rod 21a effects an, increase in the efiective pitch of fan blades 20 and thus produces an increased. flow of airthrough the radiator 11 and rearwardly over the engine. It should be noted that the power consumed by the fan is always maintained in proportion to the cooling requirements of they engine. When the engine is cold or operating below normal engine temperatures, the fan blades 20 will; remain at their substantially zero position and little power will be consumed in driving the fan.

The variable pitch fan construction heretofore described may be conveniently manually operated to reverse the pitch of the fan blades so as to drive air forwardly through the. radiator 11 to effect cleaning Of such radiator of accumulated trash To accomplish such reversal, a cupshaped actuating element 26-,is provided which is. slidably mounted within the spring support sleeve 24a and in turn slidably journals the forward end of piston rod 21a. Pushing the actuator 26 inwardly, or rearwardly with respect-to radiator 11, produces; a, corresponding. movement of; shifter; collar 22' and hence effects a reversal of the pitch of the fan blades 20. While a variety of well-known. mechanical, devices could, obviously be employed to effectthe shifting of actuator 26, this operation can be most conveniently accomplished by forming the radiator 11 with a suitable aperture 11b in alignment with actuator 26 so as to permit the manual insertion of a suitablev tool (not shown) through aperture 11b to engage actuator 26' and displace it rearwardly. In this manner, the operator may avoid. all possibility of injury from the rotat-. ing fan blades 20.

It will be noted that the one end por- From the foregoing description, it is apparent that there is here provided an unusually simple and economically manufacturable variable pitch fan unit which may be conveniently applied to existing types of internal combustion engines and which will effect the automatic regulation of the fan blade pitch as a function of engine temperature and which will further permit the convenient reversal of the pitch of the fan blades to direct a reverse flow blast of air through the radiator for cleaning purposes.

It will, of course, be understood that various details 0 construction may be varied through a wide range without departing from the principles of this invention and it is, therefore, not the purpose to limit the patent granted hereon otherwise than necessitated by the scope of the appended claims.

I claim:

l. A variable pitch fan for an internal combustion englne comprising a rotatable fan hub, a plurality of fan blades radially mounted on said hub and journaled for movement about their radial axes, an hydraulically actuated piston operatively connected to said fan blades to effect pitch adjustment thereof, resilient means opposing displacement of said piston in either direction from a neutral position corresponding to a substantially zero pitch position of said fan blades, means defining an enclosed cylinder chamber cooperable with said piston, a portion of said chamber being disposed in heat transfer relationship to said engine, and a charge of temperature respon-. sive, variable pressure fluid in said cylinder chamber, whereby said piston is actuated by said fluid in the one direction to increase the engine cooling properties ofsaid fan blades as engine temperatureincreases, and. manually operable means for displacing said piston in the opposite direction to reverse the pitch of said fan blades.

2. A variable pitch. fan for a liquid cooled internal combustion engine having a radiator, comprising a fan hub rotatably journaled behind the radiator, a plurality of fan blades radially mounted on said hub and journaled for movement about their radial axes, an hydraulically actuated piston operatively connected to said fan blades to effect pitch adjustment thereof, resilient means opposing displacement of said piston in either direction from a neutral position corresponding to a substantially zero pitch position of said fan blades, means defining an enclosed cylinder chamber cooperable with said piston, a portion of said chamber being disposed in heat transfer relationship to said engine, and a charge of temperature responsive, variable pressure fluid in said cylinder chamber, whereby said piston is actuated by said' fluid in the direction to increase the air flow through the radiator pro. duced by said. fan blades as engine temperature increases, and manually operable means for displacing said piston in the opposite direction to. reverse the pitch of said fan blades, and thereby reverse the air flow through said radiator.

3. The combination defined in claim 2 wherein said last mentioned. means comprises a rod-like extension operatively connected to said piston and extending toward said radiator, said radiator having an aperture therethrough aligned with said extension to permit manual operation of said extension.

References Cited in he file of this patent UNITED STATES PATENTS- 2,047,028 Metcalfe July 7, 1936 2,284,938 Allen, Jr. June 2, 1942 2,423,140 Earley et al. July 1, 1947 2,437,810 Earley et al Mar. 16, 1948 2,479,668 Brandon et al Aug. 23, 1949.

FOREIGN PATENTS 942,363 France Sept. 13. 1948 

